I want to build a relay controlled power socket from a controller, such as arduino. Have a manual override switch dimmer.

So to start this learning curve for myself, I have set a goal to have one socket with a lamp plugged into it, that I can turn on/off from my arduino, but still retain a manual dimmer switch on the near by wall.

I have done some reading on Triacs, and such, but decided that a 30amp 115v SSR would be a good solutions for easiness.. (unless I can get a good schematic to follow with a triac)

My desire is to have something similar to the Sparkfun tutorial below where I can send a 5v signal (externally amplified for longer distances) to a socket, and switch off power. I would like to base this on a 30amp capable chips and components, and downgrade 10-15 amp as needed when the system is expanded. My question revolves around the RELAY, and manual override from a wall switch. Some how I would like to know the dimming value, not crucial, but nice, but more importantly how do I override and turn on the socket from the switch and the arduino knows this happened? Its all about piggy backing these modules and getting the logic right, I believe the micro controller can check the state of the pole to know what it's doing, and there for, on the application end.. things will be "synced".

Any assistance with the flow and layout of these components.. or suggestions to this design would be great.